I see that the hot point is whether pros deliberately add side spin or not.
Have you seen a new driver? He holds the wheel at 10 and 2 and rotates it textbook style. As a seasoned driver, don't you sometimes make a turn by rotating the wheel with one finger, JUST BECAUSE YOU CAN?
I think once a pro knows he can do something, he will do it when the conditions are right. It may depend on his mood more than anything else, but he will do it once in a while. The above article estimates this happens in a quarter to half of their groundies. Though that might show "proof of intent" to some, I think you also need to take the "can do it so I will" approach which eventually becomes subconscious at some point.